Hi Winston,
Not much I can say with certainty, but here are a few suggestions:

>S. v. athenius ( Athens, Athenia, god of wisdom ?)
Yes this appears to be one of many shell names derived from Greek mythology.
>S. epidromis (something about running ?)
epi = situated upon; dromas (dromis), as you said, means running.  Doesn't
make a lot of sense, does it?  The shell is often called the "sail conch" in
reference to its wide extended lip, but it's difficult to directly connect
dromis with that idea.  We should keep in mind that species are sometimes
named for habits rather than physical characteristics of the shell.  Is this
species particularly "swift of foot"??  Someone who has observed it alive
would have to answer that.
>S. l. olydius (olidus = emitting a stink ? )
has the "sound" of Greek mythology but I don't have a book of mythology handy
to refer to??
>S. d. orosminus (oris = mouth ? )
perhaps from the Greek oros (= mountain)?  minus = less; so orosminus could
mean "less mountain", or more loosely translated, "a smaller hill" or
"smaller hump"??
>S. pipus (like a smoking pipe becasue of black aperture ? )
possibly from Pipa, a genus of toads??  The similarly-shaped Strombus
lentiginosus was once named Strombus rana (= frog) because of its squat,
bumpy shape. ??
>S .m. septimus ( 7th what ? )
I think this name derives from septum (a wall or partition), not from septem
(seven).  But I am not sure of the specific reference to shell structure.